fold-const.c (fold, [...]): Optimize 0 % X.

        * fold-const.c (fold, case CEIL_MOD_EXPR): Optimize 0 % X.
        (case FLOOR_MOD_EXPR, ROUND_MOD_EXPR, TRUNC_MOD_EXPR): Similarly.

From-SVN: r94376

gcc/ChangeLog

+2005-01-28  Jeff Law  <law@redhat.com>
+
+	* fold-const.c (fold, case CEIL_MOD_EXPR): Optimize 0 % X.
+	(case FLOOR_MOD_EXPR, ROUND_MOD_EXPR, TRUNC_MOD_EXPR): Similarly.
+
 2005-01-28  Kazu Hirata  <kazu@cs.umass.edu>
 
 	* cse.c (cse_reg_info_free_list, cse_reg_info_used_list,

gcc/fold-const.c

@@ -7875,7 +7875,8 @@ fold (tree expr)
     case FLOOR_MOD_EXPR:
     case ROUND_MOD_EXPR:
     case TRUNC_MOD_EXPR:
-      if (integer_onep (arg1))
+      /* 0 % X is always zero as is X % 1.  */
+      if (integer_zerop (arg0) || integer_onep (arg1))
 	return omit_one_operand (type, integer_zero_node, arg0);
       if (integer_zerop (arg1))
 	return t;